A recent report from the World Health Organization noted that for the first time, the number of people falling ill and dying from tuberculosis is declining. But with nearly one fifth of the world's population today still smoking tobacco, and with millions more exposed to second-hand smoke, progress against TB could be undermined. That's the conclusion of a new study that predicts smoking will contribute to an additional 34 million TB deaths by 2050.

The World Health Organization's efforts to control the spread of tuberculosis have focused mainly on detecting and treating active TB infections around the world. Far less effort has gone toward addressing the causes of this highly contagious respiratory disease. Dr. Anthony Fauci, director of the U.S. National Institute for Allergy and Infectious Diseases, believes the campaign against this global killer would be strengthened if we understood more clearly why people get sick with TB in the first place.

“Despite our control efforts - you still have more than a million people each year dying from TB and millions and millions getting infected. We realize that it's still a very important problem. So we have to do the practical thing (treating people) and we have to do the fundamental research things at the same time,” Fauci said.

A new study of the worldwide TB epidemic by researchers at the University of California in San Francisco concludes that tobacco use, which by itself is a major public health concern, is also an important factor that's working against TB control efforts.

“What this paper shows is that there is a false dichotomy, that you can’t control tuberculosis if you don’t control tobacco use,” said Dr. Stanton Glantz, co-author of the study and director of the University of California's Center for Tobacco Control Research and Education. He and his colleagues note that smoking does not cause tuberculosis. TB is caused by a bacterium. But smoking depresses the immune system and makes it more likely that a person with a latent lung infection will develop an active and potentially deadly case of TB.

“It (first- and second-hand smoking) increases the number of people who will get tuberculosis by about 7 percent. It increases the number of people projected to die from tuberculosis between now and 2050 by about 26 percent,” Glantz said.

Glantz believes his study, the first to identify this direct link between tobacco use and TB infection and mortality rates, should be of great interest to health policy makers and those guiding TB control programs.

“Bottom line: if you want to control the infectious disease of TB, you have to control the tobacco industry and the tobacco industry’s efforts to increase tobacco use, particularly in developing countries where TB is a big problem,” Glantz said.

Dr. Glantz's study predicts that in parts of the developing world where TB is already endemic, the situation will get worse if tobacco companies continue to expand their markets. It concludes that aggressive tobacco control measures will enable these countries not only to curb the emphysema, heart disease and lung cancer associated with smoking tobacco, but also to avert the millions of additional deaths from tuberculosis.